Ontario Progressive Conservative Leader Patrick Brown leaves Queen's Park after a press conference in Toronto on Wednesday, January 24, 2018. A woman who accused former Ontario Progressive Conservative leader Patrick Brown of sexual misconduct now says she wasn't underage at the time of the alleged incident but stresses it doesn't change the core of her allegations. THE CANADIAN PRESS/Aaron Vincent Elkaim

TORONTO - Patrick Brown has stepped up his campaign to defend himself against sexual misconduct allegations, challenging his accusers to take their complaints to police and lashing out at CTV News as the broadcaster reported one of the women quoted in its original story has now changed a key detail in her account.

In a lengthy Facebook post Wednesday, the former leader of Ontario's Progressive Conservatives accused CTV News of defamation for broadcasting the allegations from two women that date back to when he was a federal MP.

The accusations, which prompted Brown's resignation last month, have not been verified by The Canadian Press.

In late January, CTV reported that one woman, who is now 29, claimed she was still in high school and under the legal drinking age when Brown allegedly asked her to perform oral sex on him.

Another woman said she was a university student working in Brown's constituency office when he sexually assaulted her at his home, CTV reported.

Late Tuesday, CTV reported that the first accuser now said she had not been in high school or under the legal drinking age during the alleged incident. The woman said the altered timeline did not change the core of her allegations and noted she had been subject to demeaning and misogynistic comments online since the story broke.

Brown called the change in the narrative "monumental."

"Here is my message to CTV News. You lied. You defamed me," he said in his Facebook post. "And here is my message to my accusers – both of them. If you truly stand by your allegations, then I urge you to contact Barrie Police and have them lay charges."

"His attacks on our journalistic practices are groundless and wrong. CTV News continues to ask Patrick Brown if he thinks the two women accusing him of sexual misconduct are lying. He has yet to respond."

The woman who had altered her timeline on her allegations told CTV she stands by her accusations.

"There is nothing in what Patrick Brown alleges that undermines the core truth of what I have experienced with him," she said in a statement posted online by the broadcaster.

"The comments that I have been subjected to ignore altogether the abuse of power by an older sober man over a young intoxicated woman in this case."

The woman's lawyer, David Butt, told CTV it's not unusual for "collateral details" to fade over time and complainants shouldn't be blamed because it often takes years for them to find the courage to speak out.

"These sorts of issues arise routinely in historical cases and cannot be blamed on survivors, because coming forward is such a difficult act," he said.

Brown's second accuser also said she stands by her allegations, CTV reported.

Brown — who has vowed to clear his name — has said in an earlier Facebook post that both women's accounts contain discrepancies that show their accusations are false. He also alleged both accusers know CTV reporters socially, and that the broadcaster has left out contradicting witness accounts in its reports.

CTV reported the alleged incident with the first accuser happened in Brown's bedroom with the door closed, but Brown said in his Facebook post that at the time of the alleged incident, he lived in an open concept apartment and the bedroom didn't have a door.

Brown further alleged that his second accuser actually tried to kiss him while the woman he was seeing romantically was in another room.

In an interview with Global News on Wednesday, Brown again went through what he called discrepancies in the women's allegations, calling them "fictitious."

"So why all of the sudden would someone — who was a big fan, who was liking comments that I'm a great boss, a great friend and a great leader — do this?" Brown said of his second accuser.

"I want to know who put her up to this, I want to know who is behind this, because it's just horrific."

Brown's departure as Ontario Tory leader threw his party into turmoil, triggering a hastily planned leadership contest ahead of a June election.